CN112834997B - Low-scattering carrier appearance design method with rectangular opening characteristic - Google Patents
Low-scattering carrier appearance design method with rectangular opening characteristic Download PDFInfo
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- CN112834997B CN112834997B CN202110017664.9A CN202110017664A CN112834997B CN 112834997 B CN112834997 B CN 112834997B CN 202110017664 A CN202110017664 A CN 202110017664A CN 112834997 B CN112834997 B CN 112834997B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
- G01M15/02—Details or accessories of testing apparatus
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract
The application provides a low-scattering carrier appearance design method with rectangular opening characteristics, which comprises the steps of firstly constructing two first sections and two second sections which are parallel to each other, carrying out rotation operation on the first sections to obtain a first part, and connecting the vertexes of the first sections and the second sections to obtain a second part, wherein the surfaces of the first part and the second part are the low-scattering carrier appearance when a rectangular spray pipe is assembled. The design method of the low-scattering carrier appearance provided by the application only comprises two mutually parallel design sections, is simple, can obviously shorten design time, adopts a simple surface to construct the low-scattering carrier appearance, lightens design difficulty, is easy to process and manufacture, shortens design and manufacturing period and manufacturing cost, and can meet the test requirement of the radar scattering section of the aeroengine assembled with the rectangular spray pipe.
Description
Technical Field
The application belongs to the technical field of aircraft structural design, and particularly relates to a low-scattering carrier appearance design method with rectangular opening characteristics.
Background
The radar scattering signals generated by the engine rear cavity of the stealth aircraft and the edges thereof and the like account for more than 90% of the characteristic signals of the tail radar of the whole aircraft, so that the engine rear cavity radar stealth design and test are important components of the aircraft stealth design.
In the process of testing the backward RCS (radar cross section) of the engine, in order to ensure that RCS values obtained by testing are all from the inner surface of a rear cavity of the engine and the outer wall surface structure of a spray pipe, other outer surfaces of the engine are required to be shielded by using a low-scattering carrier in the process of testing the RCS. The profile design of the low scattering carrier needs to meet the following two requirements:
1) The RCS value of the low scattering carrier should be 20dBsm or more lower than that of the test target engine;
2) The low scattering carrier should be able to effectively shield the engine outer surface covered by the aircraft fuselage in the installed state.
The existing low-scattering carrier for the RCS test of an aeroengine is shown in fig. 1, wherein the left part of the low-scattering carrier 10 is shown as a low-scattering carrier, and the right part of the low-scattering carrier 10 is shown as an engine nozzle 20, and the low-scattering carrier 10 is supported by a bracket 30.
The low scattering carrier in fig. 1 effectively covers the outer surface of the engine except the engine spray pipe, simulates the actual installation state of the engine, only exposes the outer surface of the spray pipe and the rear cavity of the engine which leak outside in the installation state of the engine, and meets the RCS test state requirement of the aeroengine.
The existing low-scattering carrier for the RCS test of the aeroengine is shown in fig. 1 and 2, and aims at the test targets of the aeroengine with axisymmetric spray pipes, so that the low-scattering carrier is not suitable for the RCS test of the aeroengine with rectangular spray pipes.
In order to obtain lower RCS, the low scattering carrier shown in FIG. 1 and FIG. 2 has a complex irregular curved surface, so that the difficulty in designing the carrier shape and processing the carrier is greatly increased, and further, the design and processing period is also greatly increased.
In addition, the low scattering carrier is mostly suitable for a single test target, and is only used in the RCS test process, so that the use period is short, and therefore, the economy should be considered in the design process, and the design and manufacturing cost of the low scattering carrier with the complex irregular curved surface is necessarily increased due to the large design and processing difficulty.
Disclosure of Invention
It is an object of the present application to provide a low scattering carrier profile design method with rectangular opening features to solve or mitigate at least one of the problems of the background art.
The technical scheme of the application is as follows: a method of low scattering carrier topography having rectangular opening features, the method comprising:
s1, determining a boundary section of a rectangular spray pipe and a non-exposed part of a low scattering carrier, wherein the boundary section comprises a width W and a height H, and determining the length L of the non-exposed part of the low scattering carrier;
s2, constructing a first section SEC1 and a second section SEC2 which are parallel to each other, wherein:
the outline of the first section SEC1 is rectangular, four vertexes of the rectangular outline are P1, P2, P3 and P4 in sequence, the length of a side P1P2 is equal to the width W, and the length of a side P2P3 is equal to the height H;
the contour of the second section SEC2 is hexagonal, the vertices of the hexagonal contour are P5, P6, P7, P8, P9, P10 in sequence, the midpoints of the sides P5P6 and P8P9 are points C1, C2, respectively, the contour of the second section SEC2 is symmetrical about the line segment C1C2 and the line segment P7P10, the length of the side P5P6 is equal to the width W, and the vertical distance between the sides P5P6 and P8P9 is equal to the height H;
s3, rotating the edges C1P6, P6P7, P7P8 and P8C2 by 180 degrees by the line segment C1C2 in the second section SEC2 to obtain a first Part1 with the surfaces A1, A2, A3 and A4;
the connecting line P1P5P6P2 forms a rectangular surface A5, the connecting line P4P9P8P3 forms a rectangular surface A9, and the rectangular surface A5 and the rectangular surface A9 have the same shape;
the connecting line P2P6P7 forms a right triangle surface A6, the connecting line P3P8P7 forms a right triangle surface A8, the connecting line P1P5P10 forms a right triangle surface A12, the connecting line P4P9P10 forms a right triangle surface A10, and the right triangle surfaces A6, A8, A10 and A12 have the same shape;
the connecting line P2P3P7 forms an isosceles triangle surface A7, the connecting line P1P4P11 forms an isosceles triangle surface A11, and the isosceles triangle surfaces A7 and A11 have the same shape;
rectangular faces A5, A9, right-angled triangular faces A6, A8, A10, A12 and isosceles triangular faces A7, A11 form a second Part2;
s4, enabling the length K of the geometric center connecting line O1O2 of the first section SEC1 and the second section SEC2 to meet the following conditions: k is more than or equal to L and K is more than or equal to H/tan (alpha/2), alpha is the angle of < P6P7P8 in the hexagonal outline;
s5, the surfaces of the first part1 and the second part2 obtained according to the steps S1 to S4 are the shapes of the low-scattering carriers when the rectangular spray pipe is assembled.
Further, in the second section SEC2, the angle α formed by the side P6P7 and the side P7P8 is smaller than 90 °.
Further, in step S3, the method further includes:
determining a vertex P11, wherein the vertex P11 is positioned on an extension line of a connecting line O1O2, and the connecting lines P11P1P2, P11P2P3, P11P3P4 and P11P4P1 obtain four triangular surfaces;
the method comprises the steps of obtaining a cylindrical surface by taking a connecting line O1O2 as a rotation center and taking half of a height H as a rotation radius, wherein the cylindrical surface is tangent to the triangular surface to obtain a surface A13 and a surface A16 with the same shape, and the triangular surface is remained to obtain a surface A14, a surface A17, a surface A15 and a surface A18, wherein the surface A14 and the surface A17 are isosceles triangles with the same shape, the surface A15 and the surface A18 are the same in shape, the surface A15 is coplanar with the surface A7, and the surface A18 is coplanar with the surface A11;
face a13, face a14, face a15, face a16, face a17, face a18 constitute a third portion Part3.
Further, the method further comprises the following steps:
s6, the surfaces of the first Part1, the second Part2 and the third Part3 obtained according to the steps S1 to S4 are the shapes of the low-scattering carrier which are not assembled with rectangular spray pipes and are used for RCS test independently.
In addition, the application also provides: a low scattering carrier suitable for use in aero-engine RCS testing, the low scattering carrier having a profile obtained by the low scattering carrier profile design method having rectangular opening features as described in any of the above.
The low-scattering carrier appearance design method of the application has the following advantages:
1) The design method is simple, and the design man-hour can be obviously shortened;
2) The profile of the low-scattering carrier is constructed by adopting a simple profile, so that the design difficulty is reduced, and the design period is shortened;
3) The low scattering carrier is constructed by adopting a simple surface, so that the processing and the manufacturing are easy, and the manufacturing cost and the period can be reduced;
4) The RCS test requirement of the aeroengine assembled with the rectangular spray pipe can be met, and the low-scattering carrier appearance obtained by design can have a lower RCS value by controlling the included angle alpha and the length K of the line segment O1O2 in the figure 3.
Drawings
In order to more clearly illustrate the technical solution provided by the present application, the following description will briefly refer to the accompanying drawings. It will be apparent that the figures described below are merely some embodiments of the application.
FIG. 1 is a schematic diagram of a low scattering carrier for aeroengine RCS testing.
FIG. 2 is a schematic view of an aircraft engine equipped with a rectangular nozzle according to the present application
Fig. 3 is a diagram of the low scattering carrier profile design process in the present application.
Fig. 4 is a schematic representation of Part1, part2, part3 of the profile of the low scattering carrier of the present application.
Fig. 5 is a schematic view based on the K1 direction in fig. 4.
Fig. 6 is a schematic view based on the sum K2 in fig. 4.
Fig. 7 is a schematic view of the assembly of a low scattering carrier with an aircraft engine fitted with a rectangular nozzle according to the application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application become more apparent, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application.
In order to solve the problems that the existing low-scattering carrier is mostly complex and irregular curved surfaces, and the design and processing difficulties are high, so that the low-scattering carrier is large in design and manufacturing period and manufacturing cost and not suitable for the RCS test of an aeroengine equipped with a rectangular spray pipe, and the like, the application provides a low-scattering carrier appearance design method which is suitable for the RCS test of the aeroengine equipped with the rectangular spray pipe.
As shown in FIG. 2, the rectangular Nozzle nozzles of the aeroengine is the part which needs to be exposed during RCS test, namely the exposed part; main is the engine part which needs to be shielded by a low scattering carrier during RCS test, namely the non-exposed part. The plane SEC0 is a boundary section of the rectangular Nozzle nozle and the non-exposed part Main, wherein the contour of the boundary section SEC0 is rectangular, the width is W, the height is H, and the length of the non-exposed part Main is L.
The low-scattering carrier appearance design method of the present application firstly constructs two sections parallel to each other, as shown in fig. 3, specifically a first section SEC1 and a second section SEC2, where the first section SEC1 and the second section SEC2 divide the low-scattering carrier appearance into a first Part1, a second Part2 and a third Part3.
As shown in fig. 3, the contour of the first section SEC1 is rectangular, four vertexes of the rectangular contour are P1, P2, P3, and P4, the length of the side P1P2 is equal to the width W of the boundary section SEC0, and the length of the side P2P3 is equal to the height H of the boundary section SEC 0.
As further shown in fig. 3, the profile of the second section SEC2 is hexagonal, the vertices of the hexagonal profile are P5 to P10 in sequence, the points C1 and C2 are the midpoints of the sides P5P6 and P8P9, respectively, the profile of the second section SEC2 is symmetrical with respect to the line segment C1C2 and the line segment P7P10, the length of the side P5P6 is equal to the width W of the demarcation section SEC0, and the vertical distance between the side P5P6 and the side P8P9 is equal to the height H of the demarcation section SEC 0. Preferably, the angle α between the side P6P7 and the side P7P8 is less than 90 °.
Referring to fig. 4 to 6, the first portion Part1 is composed of a face A1, a face A2, a face A3, and a face A4. The surfaces A1, A2, A3, and A4 are formed by line segments C1P6, P8C2, P7P8, and P6P7 rotating 180 ° around the line segment C1C2, respectively.
The second Part2 consists of the faces A5 to a 12. The surface A5 is rectangular and is formed by line segments P1P5, P5P6, P6P2, and P2P 1. The surface A6 is a right triangle and is formed by line segments P6P7, P7P2, and P2P 6. The surface A7 is an isosceles triangle and is formed by line segments P2P7, P7P3, and P3P 2. The surfaces A6, A8, a12, a10 are the same in shape and size, the surfaces A7 and a11 are the same in shape and size, and the surfaces A5 and A9 are the same in shape and size.
The third Part3 consists of the faces a13 to a 18. The surface A13 is a cylindrical surface, the radius of gyration of the surface A13 is half of the height H of the demarcation section SEC0, and the surface A13 is tangent to the surface A14 and the surface A5; the surface A14 is an isosceles triangle; face a15 is coplanar with face A7; face a18 is coplanar with face a 11; face a14, face a15, face a17, face a18 share the same vertex P11; the surfaces a13, a14, a15 are the same as the shapes and sizes of a16, a17, a18, respectively.
The first section SEC1 and the second section SEC2 are parallel to each other, the points O1 and O2 are the geometric centers of the first section SEC1 and the second section SEC2 respectively, the first section SEC1 and the second section SEC2 are perpendicular to the line segment O1O2, and the length K of the line segment O1O2 simultaneously meets the following 2 conditions:
1)K≥L；
2)K≥H/tan(α/2)。
the external shape or the external surface of the first Part1, the second Part2 and the third Part3 obtained according to the method is the shape of the low-scattering carrier. Fig. 7 is a schematic view of the low scattering carrier profile obtained according to the method described above and overlaid on an aeroengine equipped with a rectangular nozzle, and the third portion Part3 of the low scattering carrier profile in fig. 3 or fig. 4 is not included, where the end of the second portion Part2 connected to the third portion Part3 forms a rectangular opening, and the third portion Part3 is only used for RCS testing of the low scattering carrier alone.
The low-scattering carrier appearance design method has the following advantages:
1) The design method is simple, and the design man-hour can be obviously shortened;
2) The profile of the low-scattering carrier is constructed by adopting a simple profile, so that the design difficulty is reduced, and the design period is shortened;
3) The low scattering carrier is constructed by adopting a simple surface, so that the processing and the manufacturing are easy, and the manufacturing cost and the period can be reduced;
4) The RCS test requirement of the aeroengine assembled with the rectangular spray pipe can be met, and the low-scattering carrier appearance obtained by design can have a lower RCS value by controlling the included angle alpha and the length K of the line segment O1O2 in the figure 3.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (5)
1. A method of designing a low scattering carrier profile having rectangular opening features, the method comprising:
s1, determining a boundary section of a rectangular spray pipe and a non-exposed part of a low scattering carrier, wherein the boundary section comprises a width W and a height H, and determining the length L of the non-exposed part of the low scattering carrier;
s2, constructing a first section SEC1 and a second section SEC2 which are parallel to each other, wherein:
the outline of the first section SEC1 is rectangular, four vertexes of the rectangular outline are P1, P2, P3 and P4 in sequence, the length of a side P1P2 is equal to the width W, and the length of a side P2P3 is equal to the height H;
the contour of the second section SEC2 is hexagonal, the vertices of the hexagonal contour are P5, P6, P7, P8, P9, P10 in sequence, the midpoints of the sides P5P6 and P8P9 are points C1, C2, respectively, the contour of the second section SEC2 is symmetrical about the line segment C1C2 and the line segment P7P10, the length of the side P5P6 is equal to the width W, and the vertical distance between the sides P5P6 and P8P9 is equal to the height H;
s3, rotating the edges C1P6, P6P7, P7P8 and P8C2 by 180 degrees by the line segment C1C2 in the second section SEC2 to obtain a first Part1 with the surfaces A1, A2, A3 and A4;
the connecting line P1P5P6P2 forms a rectangular surface A5, the connecting line P4P9P8P3 forms a rectangular surface A9, and the rectangular surface A5 and the rectangular surface A9 have the same shape;
the connecting line P2P6P7 forms a right triangle surface A6, the connecting line P3P8P7 forms a right triangle surface A8, the connecting line P1P5P10 forms a right triangle surface A12, the connecting line P4P9P10 forms a right triangle surface A10, and the right triangle surfaces A6, A8, A10 and A12 have the same shape;
the connecting line P2P3P7 forms an isosceles triangle surface A7, the connecting line P1P4P11 forms an isosceles triangle surface A11, and the isosceles triangle surfaces A7 and A11 have the same shape;
rectangular faces A5, A9, right-angled triangular faces A6, A8, A10, A12 and isosceles triangular faces A7, A11 form a second Part2;
s4, enabling the length K of the geometric center connecting line O1O2 of the first section SEC1 and the second section SEC2 to meet the following conditions: k is more than or equal to L and K is more than or equal to H/tan (alpha/2), alpha is the angle of < P6P7P8 in the hexagonal outline;
s5, the surfaces of the first part1 and the second part2 obtained according to the steps S1 to S4 are the shapes of the low-scattering carriers when the rectangular spray pipe is assembled.
2. A low scattering carrier shape design method with rectangular opening features as claimed in claim 1, characterized in that in the second section SEC2 the angle α formed by the side P6P7 and the side P7P8 is smaller than 90 °.
3. The low scattering carrier shape design method with rectangular opening feature as claimed in claim 1 or 2, further comprising, in step S3:
determining a vertex P11, wherein the vertex P11 is positioned on an extension line of a connecting line O1O2, and the connecting lines P11P1P2, P11P2P3, P11P3P4 and P11P4P1 obtain four triangular surfaces;
the method comprises the steps of obtaining a cylindrical surface by taking a connecting line O1O2 as a rotation center and taking half of a height H as a rotation radius, wherein the cylindrical surface is tangent to the triangular surface to obtain a surface A13 and a surface A16 with the same shape, and the triangular surface is remained to obtain a surface A14, a surface A17, a surface A15 and a surface A18, wherein the surface A14 and the surface A17 are isosceles triangles with the same shape, the surface A15 and the surface A18 are the same in shape, the surface A15 is coplanar with the surface A7, and the surface A18 is coplanar with the surface A11;
face a13, face a14, face a15, face a16, face a17, face a18 constitute a third portion Part3.
4. A method of contouring a low scattering carrier having rectangular opening features as defined in claim 3, further comprising:
s6, the surfaces of the first Part1, the second Part2 and the third Part3 obtained according to the steps S1 to S4 are the shapes of the low-scattering carrier which are not assembled with rectangular spray pipes and are used for RCS test independently.
5. A low-scattering carrier suitable for aeroengine RCS testing, characterized in that the profile of the low-scattering carrier is obtained by the low-scattering carrier profile design method with rectangular opening features according to any of claims 1 to 4.
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| CN202110017664.9A CN112834997B (en) | 2021-01-07 | 2021-01-07 | Low-scattering carrier appearance design method with rectangular opening characteristic |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113419224A (en) * | 2021-06-07 | 2021-09-21 | 西北工业大学 | Axisymmetric double-emission low-scattering carrier for RCS test and application method thereof |
| CN113418937B (en) * | 2021-06-08 | 2022-12-09 | 西北工业大学 | Rear-body-replaceable ultra-compact low-scattering carrier of aircraft engine |
| CN113532865B (en) * | 2021-06-24 | 2022-06-07 | 中国航发沈阳发动机研究所 | Low-scattering carrier suitable for various engines |
| CN113687323B (en) * | 2021-10-26 | 2022-03-08 | 中国航发四川燃气涡轮研究院 | Low-scattering shell for binary vector engine and application thereof |
| CN114355311B (en) * | 2022-03-10 | 2022-08-12 | 成都飞机工业（集团）有限责任公司 | Low-scattering carrier for RCS (Radar Cross section) test of airfoil leading edge wave-absorbing structure and test method |
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